| Summary: | 碩士 === 國防醫學院 === 生物化學研究所 === 103 === Abstract:Tight junctions have the barrier function in the endothelium to prevent even small molecules from leaking. The disruption of tight junctions in blood vessel endothelial cells leads to many cardiovascular and inflammatory diseases, such as atherosclerosis and cancer. High fat diet-induced arachidonic acid (AA) metabolite, 15(S)-HETE, and bacterial component, lipopolysaccharide (LPS), both can impair tight junctions via dissociation of transmembrane adhesion proteins, Claudin-1 and Claudin-5, and peripheral membrane protein, zona occludens-2 (ZO-2), thereby bringing out abnormal cell-cell barrier permeability which initiates inflammatory responses in endothelial cells. Our previous studies found that a tryptophan metabolite, 5-methoxytryptophan (5-MTP), released from fibroblast inhibits COX-2-induced systemic inflammation which involves in cancer growth and metastasis. The integrity of endothelium have a crucial role in cancer, inflammatory diseases and vascular diseases progression, and we thus hypothesize that 5-MTP may support the tight junctions in endothelial cell to decrease inflammation and cancer progression. In this study, we used cell-cell barrier permeability assay to demonstrate that 5-MTP decreased the LPS/15(S)-HETE-induced lesion of tight junctions and endogenous 5-MTP in HUVECs maintained the ability of tight junctions which observed in anti-5-MTP antibody neutralization assay. We found that LPS/15(S)-HETE does not alter the tight junctions proteins expression but impair ZO-2 cellular localization; however, in immunoprecipitation assay, 5-MTP could inhibit not only the LPS/15(S)-HETE-induced tight junctions proteins dissociation between ZO-2 and Claudin-1/-5 but also the phosphorylation of ZO-2. LPS/15(S)-HETE stimulation may induce HUVECs cytokines released which promote macrophage migration. We indicated that pretreatment of 5-MTP on HUVECs reduced LPS/15(S)-HETE-induce macrophage migration significantly. In Evans blue assay, 5-MTP-injected mouse could protect from LPS/15(S)-HETE-induced lesion of tight junctions in vivo. Collectively, 5-MTP has a potentiality to sustain the integrity of endothelium, thereby alleviating inflammation and cancer progression.
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